Mine was getting worse in the colder weather, and then suddenly in the past 2 days, it stopped.
It was accompanied by acceleration vibration and jolting. One mechanic said it could be that the rollers have gotten dirty, but at 5200 miles?
I continue to insist to him and the other mechanics that it happened after the throttle cable adjustment during my last service.
I am currently very happy that it's stopped, and if it does recur I will certainly hold the guys at Bert's accountable.
My best guess is that when they originally tightened the throttle cable for faster accel it was causing some hiccups that resolved when the cable stretched a little bit more again.